Steel-structure demolition method

ABSTRACT

A steel-structure demolition method for demolishing a steel structure by causing the steel structure to collapse, the steel-structure demolition method includes: demolishing the steel structure in such a fashion that the steel structure is cut along a cutting line extending in a direction perpendicular to a depth direction thereof when having collapsed.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit of priority upon Japanese Patent Application No. 2013-091122 filed on Apr. 24, 2013, of which full contents are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method for demolishing the steel structures.

2. Description of the Background Art

Methods for effective blast demolition of the concrete structures have already been publicly known as described in patent document 1 (Japanese patent publication No. H6-264627) and patent document 2 (Japanese patent publication No. 2003-307038).

The targets of conventional methods for demolition as mentioned above have been the concrete structures, but have not been the steel structures. Furthermore, there have been no techniques for which consideration is taken of the reduction of the height of demolished structures.

SUMMARY OF THE INVENTION

A method according to the present invention to solve the above problems is a steel-structure demolition method for demolishing a steel structure by causing the steel structure to collapse, the steel-structure demolition method including: demolishing the steel structure in such a fashion that the steel structure is cut along a cutting line extending in a direction perpendicular to a depth direction thereof when having collapsed.

In the above steel-structure demolition method according to the present invention, the above demolishing the steel structure includes: initially cutting the steel structure along a plurality of cutting lines extending in a direction perpendicular to the depth direction so as to divide the steel structure into a plurality of longitudinal layers such that the plurality of longitudinal layers are aligned in the depth direction; subsequently cutting a lower portion of a front support pillar of a longitudinal layer in a foremost row out of the plurality of longitudinal layers as well as a diagonal member linked thereto so as to cut and remove a lower layer of pillar bearing an axial force by blasting, thereby causing the longitudinal layer in the foremost row to deform largely in a horizontal direction and collapse; and causing a longitudinal layer in a next row out of the plurality of longitudinal layers to collapse in a similar fashion after the longitudinal layer in the foremost row has collapsed.

In the above steel-structure demolition method according to the present invention, the above demolishing the steel structure includes: cutting a lower portion of a front support pillar of a longitudinal layer in a foremost row of the steel structure as well as a diagonal member linked thereto so as to cut and remove a lower layer of pillar bearing an axial force by blasting, thereby causing the steel structure as a whole to deform largely in a horizontal direction and horizontally collapse; and cutting the steel structure along a cutting line extending in a direction perpendicular to the depth direction by blasting during a horizontal collapse.

According to the above-mentioned steel-structure demolition method according to the present invention, at least one of the following effects can be achieved:

[1] A steel structure is not demolished integrally but is demolished in two separate stages such that, after a longitudinal layer in a front row of the steel structure is caused to collapse, a longitudinal layer in a next row is caused to collapse over the longitudinal layer in the front row having already collapsed.

[2] Accordingly, the longitudinal layer having collapsed earlier is crushed by the longitudinal layer collapsing thereover later, and the layers are compressed in sequence to be staked, thereby reducing the height of the stacked layers.

[3] Consequently, the overall height of the demolished steel structure can be significantly reduced in comparison with the depth of the steel structure prior to being demolished.

[4] As a result of such reduction of the height of the debris produced by the demolition, subsequent processes can be carried out safely at low cost.

BRIEF DESCRIPTION OF THE DRAWINGS

For more thorough understanding of the present invention and advantages thereof, the following descriptions should be read in conjunction with the accompanying drawings, in which:

FIG. 1 depicts a conceptual view showing a steel-structure demolition method according to the present invention.

FIG. 2 depicts an explanatory view showing a process of dividing the steel structure into front and rear longitudinal layers in a lateral direction.

FIG. 3 depicts an explanatory view showing a process of cutting a support pillar and the like in a lower portion of the front longitudinal layer out of longitudinal layers obtained by dividing the steel structure.

FIG. 4 depicts an explanatory view showing a process of allowing the front longitudinal layer to collapse.

FIG. 5 depicts an explanatory view showing a process of cutting a support pillar and the like in a lower portion of the rear longitudinal layer.

FIG. 6 depicts an explanatory view showing a state where the rear longitudinal layer collapses over the front longitudinal layer.

FIG. 7 depicts an explanatory view showing a process of cutting a support pillar and the like in a lower portion of the steel structure prior to being divided.

FIG. 8 depicts an explanatory view showing a process of dividing the steel structure into longitudinal layers during collapse thereof.

DESCRIPTION OF EMBODIMENTS OF THE INVENTION

Hereinafter, preferred embodiments of a steel-structure demolition method according to the present invention will be described in detail by referring to the drawings.

EXAMPLES [1] Concept of Demolition in the Present Invention

A target of a demolition method according to the present invention is a steel structure A constructed as a truss.

The scenario is effective in demolition of a structure A having a large depth when viewed from the front thereof, in particular, as shown in FIG. 1.

In such a scenario, the features according to the present invention can be exploited effectively if the structure A is divided into a plurality of longitudinal layers A1, A2, and so on along a plurality of cutting lines each defined as extending in a direction substantially perpendicular to a depth direction of the structure A, and the plurality of longitudinal layers A1, A2, and so on are caused to collapse one by one in sequence. However, the present invention is not limited to being applied only to the structure A of the type shown in FIG. 1.

The demolition method according to the present invention has the features of demolishing the steel structure A in such a fashion that the steel structure A is cut along a cutting line extending in a direction perpendicular to the depth direction at least when having finished collapsing.

Note that, in the present invention, the expression “direction perpendicular to” is used not to indicate that an angle of mathematically precise 90° is formed with respect to a direction of collapse or a depth direction but to substantially indicate that a direction intersects the direction of collapse or the depth direction.

[2] Method of Division Prior to Collapse

As the fundamental concept, the present invention is characterized by, as mentioned above, demolishing the steel structure A in such a fashion that the steel structure A is cut along a cutting line extending in a direction perpendicular to the depth direction when having finished collapsing. More specifically, two types of methods can be adopted.

One of such two types of methods is a method of finishing division of the steel structure A prior to collapse of the steel structure A.

[2-1] Formation of Longitudinal Layers (FIG. 2)

In the present method, the steel structure A is initially cut along a plurality of cutting lines extending in a direction perpendicular to the depth direction so that a plurality of longitudinal layers A1, A2, and so on are formed.

Such cutting is performed by blasting with the use of explosives attached to horizontal members arranged across a plurality of scheduled cutting lines and attached to diagonal members linked to the horizontal members in the structure A.

Techniques to cut steel material by blasting are publicly known.

By such cutting, the steel structure A can be divided into a plurality of longitudinal layers A1, A2, and so on each extending in a direction perpendicular to the depth direction.

As mentioned above, an example according to the present invention has the features of initially dividing the structure A into a plurality of longitudinal layers A1, A2, and so on such that the plurality of longitudinal layers are aligned in the depth direction.

[2-2] Collapse of Foremost Row (FIGS. 3 and 4)

After having divided the steel structure A into the plurality of longitudinal layers A1, A2, and so on each extending in a direction perpendicular to the depth direction, a lower portion of a front support pillar a of the longitudinal layer A1 in the foremost row as well as a diagonal member b linked thereto are initially cut.

Such cutting is also performed by blasting with the use of explosives attached to each member.

In the process, a lower layer of front pillar a bearing an axial force can be cut and removed by blasting, thereby causing the longitudinal layer A1 in the foremost row to deform largely in a horizontal direction and horizontally collapse.

[2-3] Collapse of Next Layer (FIG. 5)

After the longitudinal layer A1 in the foremost row is caused to collapse, the longitudinal layer A2 in the next row is caused to collapse in a similar fashion. Also in the process, by cutting and removing a lower layer of pillar and diagonal member bearing an axial force of the longitudinal layer A2 in the next row by blasting with the use of explosives, the longitudinal layer A2 in the next row is caused to deform largely in a horizontal direction and horizontally collapse.

The above operation is carried out for each of the divided longitudinal layers A1, A2, and so on in the order in which the forward layer collapses and thereafter the next layer collapses.

[2-4] Effects of Collapse of Next Layer (FIG. 6)

As have been mentioned, the longitudinal layer A2 in the next row is caused to collapse over the longitudinal layer A1 in the foremost row having already collapsed.

Accordingly, the longitudinal layer A1 in the foremost row having collapsed earlier is crushed by the longitudinal layer A2 in the next row collapsing thereover later,

As a result, a layer having collapsed earlier is compressed by a shock of collapse of a next layer collapsing later in sequence to be staked, thereby reducing the height of the stacked layers.

[3] Method of Division During Collapse

In the above-mentioned method, the steel structure A is divided in advance in a direction perpendicular to the depth direction, and thereafter each of the longitudinal layers A1, A2, and so on is caused to collapse.

On the other hand, an example shown below is a method for dividing the steel structure A in a direction perpendicular to the depth direction during collapse of the entire steel structure A, i.e., from when collapse is started to when collapse is finished.

[3-1] Collapse of Entire Structure (FIG. 7)

A lower portion of a front support pillar a as a truss of the steel structure A as well as a diagonal member b linked thereto are cut by blasting.

At this time, in order to create imbalances in the bearing force with the aim of causing the structure A to collapse in one direction, the blast destruction in a wedge pattern, when viewed from the side thereof, is carried out.

In such a fashion, the lower layer of support pillar a and diagonal member b are cut and removed by blasting with the use of explosives such that the axial force of the steel structure A is born by the lower layer in an imbalanced fashion, which results in causing the entire steel structure to deform largely in a horizontal direction and horizontally collapse

[3-2] Division During Collapse (FIG. 8)

In the midst of horizontal collapse of the steel structure A, i.e., from when collapse is started to when collapse is finished, the steel structure A is cut by blasting along a cutting line extending in a direction perpendicular to the depth direction.

In other words, in the present method, the structure A is not divided into front and rear layers in a lateral direction when collapse is started, but is divided into a front longitudinal layer A1 and a rear longitudinal layer A2 during collapse so that the front and rear longitudinal layers A1, A2 are caused to collapse at a minute time interval therebetween.

According to such a method, the entire structure A can be demolished at once, and therefore no threat is posed to workers even if unpredictable crash occurs due to redistribution of stress during demolition.

[3-3] Setting of Timing of Collapse

As mentioned above, an example according to the present invention is a method for cutting the steel structure A by blasting along a cutting line extending in a direction perpendicular to the depth direction in a minute period of time, i.e., from when collapse of the steel structure A is started to when collapse of the steel structure A is finished.

For this reason, an elaborate study is required on: the positions at which the cutting is performed by blasting; a time interval between blasting for demolition as a whole and blasting for division; and timings thereof.

Such study may be conducted by adopting a blast demolition simulation technique using, e.g., an ASI-Gauss method. However, the present invention is not limited to being applied with the ASI-Gauss method.

[4] Other Cutting Methods

In the above-mentioned methods, the cutting is performed by blasting with the use of explosives. Alternatively, any publicly-known cutting method may be adopted such as cutting associated with welding, a cutter, a circular saw, and the like.

REFERENCE NUMERALS

-   A: structure -   A1: front longitudinal layer -   A2: next longitudinal layer 

What is claimed is:
 1. A steel-structure demolition method for demolishing a steel structure by causing the steel structure to collapse, the steel-structure demolition method comprising: demolishing the steel structure in such a fashion that the steel structure is cut along a cutting line extending in a direction perpendicular to a depth direction thereof when having collapsed.
 2. The steel-structure demolition method according to claim 1, wherein said demolishing the steel structure comprises: initially cutting the steel structure along a plurality of cutting lines extending in a direction perpendicular to the depth direction so as to divide the steel structure into a plurality of longitudinal layers such that the plurality of longitudinal layers are aligned in the depth direction; subsequently cutting a lower portion of a front support pillar of a longitudinal layer in a foremost row out of the plurality of longitudinal layers as well as a diagonal member linked thereto so as to cut and remove a lower layer of pillar bearing an axial force by blasting, thereby causing the longitudinal layer in the foremost row to deform largely in a horizontal direction and collapse; and causing a longitudinal layer in a next row out of the plurality of longitudinal layers to collapse in a similar fashion after the longitudinal layer in the foremost row has collapsed.
 3. The steel-structure demolition method according to claim 1, wherein said demolishing the steel structure comprises: cutting a lower portion of a front support pillar of a longitudinal layer in a foremost row of the steel structure as well as a diagonal member linked thereto so as to cut and remove a lower layer of pillar bearing an axial force by blasting, thereby causing the steel structure as a whole to deform largely in a horizontal direction and horizontally collapse; and cutting the steel structure along a cutting line extending in a direction perpendicular to the depth direction by blasting during a horizontal collapse. 